With RGWs configured in a load balancer, quota stats cache can possibly run into unbound values. We have found errors like below in our clusters running Jewel. This happens when PUT and DELETE operations do not hit the same RGW and an eventual update_stats() from a DELETE operation tries to decrement the stats cache. This can be easily verified by having RGWs configured in a load balancer(I've used HAProxy in RR mode) and running a script to upload/delete objects, with the user quota enabled.